Firing mechanism for automatic firearms with nonaxial rectilinear breechblock motion



2 c. E. SIMPSO 2 594 359 Apnl FIRING MEC ISM FOR AUTOMA FIREARMS WITH NONAXIA EIC'I'ILINEAR BREECHLOCK MOTION Original Filed June 7, 1946 2 SHEETS-SHEET 1 FIE-l...

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April 29, 1952 c. SIMPSON 2,594,359

I FIRING MECHAN ISM AUTOMATIC FIREARMS WITH NONAXIAL RECTILINEAR BREECHLOCK MOTION Original Filed June 7, 1946 SHEETS$HEET 2 3 rwwrytop Elurehn eE-5:i.m .scln

Patented Apr. 29, 1952 FIRING MECHANISM FOR AUTOMATIC FIRE- ARMS WITH NONAXIAL RECTILINEAR BREECHBLOCK MOTION Clarence E. Simpson, Springfield, Mass., assignor to the United States of America as represented by the Secretary of War Original application June 7, 1946, Serial No. 675,124. Divided and this application March 19, 1948, Serial No.- 15,945

(Granted under the act of March 9, 1883, as amended April 30, 1928; 370 O. G. 757) 5 Claims.

The inventiondescribed hereinmay be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

' This invention relates to a firing mechanism for firearms of the automatic type wherein the breech block is slidably carried by a breech block carrier for movement in a horizontal and vertical plane.

This application is a division of my copending application for Firearms, Serial No. 675,124 filedv June 7, 1946 and now matured into Patent No. 2,555,379.

It is an object of this invention to provide a firing mechanism for a firearm of the automatic type wherein the breech block of such firearm is slidably mounted on a breech block carrier.

- Another object of this invention is to provide a firing mechanism for an automatic firearm wherein the recoiling movement of the breech members is utilized to cook such firing mechanism.

A specific object of this invention is to provide a firing mechanism for a firearm of the type disclosed in my copending application Serial No. 675,124 filed June 7, 1946, for Firearms and now matured into Patent No. 2,555,379.

Thespecific nature of the invention as well as other-objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawingsin which:

Fig. In a fragmentary longitudinal sectional view of the firearm embodying this invention.

Fig. 2 is a fragmentary, enlarged, detail, sectional view showing the main elements of the firing mechanism. Fig. 3 is a fragmentary illustrating the sear release mechanism.

Fig. 4v is an enlarged: detail view of the trigger.

view of the main breech elements of the firearm showing thecocking lever on the left hand side thereof. Y

Fig. 9 is a horizontal sectional'view taken along the line 99 of Fig. 3. q i

a; firearm of the type described and fully disclosed-in the'abov'e-mentioned copending ap-' 'plication -there is utilized a breech mechanism of plan viewof Fig. 1

novel construction which must necessarily employ a firing mechanism of substantially radical construction from those hitherto used in the art for discharge of a cartridge.

Briefiy such firearm comprises essentially a receiver I0, a barrel II, a barrel extension l2, a breech block l3 and abreech block carrier l4. Receiver It). comprises two oppositely disposed parallel side plates 17. Such side platesare sep-,

arated by front and rear spacers (not. shown).

A bottom plate I8 is provided underneath the side plates I! and is disposed towards the rear.

of receiver l0. Extension I2 is secured to barrel ll preferably by threads [5 and such extension i2 is slidably mounted in receiver Ill for longitudinal movement by guide ribs (not shown) which engage corresponding ways l6 provided in each side plate of receiver [0. The forward end of barrel II is supported by a front barrel hearing support (not shown) so that such barrel is horizontally disposed for longitudinal reciprocating movement.

Barrel extension I2 is, a substantially rec tangular member and is provided with a vertically disposed slot I 9' at the rear end thereof which is shaped to receive breech block l3 as will be later described. Suitable locking lugs (not shown) are provided in such slot. Breech block I3 is likewise slidably mounted in receiver I!) for longitudinal reciprocating movement and such breech block is provided with suitable ribs (not shown) for engagement with ways I6. Breech block I 3 comprises a substantially v-shaped member having a vertical arm 20 and an upward- 'ly and rearwardly sloping arm 2|. A cartridge feeding T-slot 22 is provided on the forward vertical face on arm 20 as shown in Fig. 1. On the rear face of the rearwardly sloped arm 2| of breech block I3 there is provided a T-shaped rib (not shown) .which slidably connects breech block I3 to breech block carrier M as will be later de scribed. ,A pluralityof locking lugs (not shown), engage the corresponding lugs on the barrel extension l2 to locksuch breech block thereto. Near the bottom of breech block l3 there is provided a rearwardly opening counterbored'hori zontal hole 23 of suitable shape to receive a firing pin 24. ,7

Firing pin 24 Figs. 1, 2 and 8) is provided with an integral head 25, the rear end surface of which is sloped as shown at 26 for a purpose to be described. A spring 21 surrounds the body portion of firing pin 24 and abutshead 25 and the.bot-.

tom'ozf the counterbored portion of hole 23 to bias firing pin 24 rearwardly thus retracting the forward end of such firing pin from the face of cartridge feeding T-slot 22. A longitudinal slot (not shown) is provided in head 25 f firing pin 24 which is engaged by a transverse pin provided in breech block I3 (not shown) so that the sloped end 26 of firing pin 24 is maintained-in the position shown in Fig. 2. Firing pin- 24: is retainedwithin hole 23 by a plate 28 which is inserted in against plate 28 thereby limiting the rearward travel of such firing pin.

Breech block carrier I4 is likewise slidably mounted in receiver II) in a manner similar to that of breech block I3. Such carrier comprises a horizontal arm 31 and an integral upwardly inclined arm 32 as shown in Figs. 1' and 2'. A transverse hole 33 is provided in the lower rear corner of carrier I4 as shown in Fig. 1 in which is inserted a pin 34 to connect such carrier with a carrier slide 35. On the forward face of inclined arm 32 of carrier I4 there is provided a suitable T-slot (not shown) which is engaged by the corresponding rib provided on breech block I3 toslidably secure such block to carrier M. A longitudinal rectangular recess 36 is provided on the front face of inclined arm 32 of carrier I4 to slidably mount a hammer 31'. Hammer 31 is a substantiallyrectangular member provided'with an integral lug 38 on the upper surface-thereof as shown in Figs. 1, 2and 8. Lug 38 has a sloped forwardly facing surface 39 which mates with sloped surface on the end of firing pin 24 when such hammer rests within recess 361 A rearwardly opening hole. 41!, provided in hammer 31 along the longitudinal axis'thereof houses a helical hammer spring 4|. Such spring is retained within hole by a. headed rod-like. member 42. The head portion of head memberi42 rests on top of inclined arm 32 to seal the end ofa hole 43 which communicates with the rectangular recess 36. Member 42. in turn isretainedwithin hole 43 by a pin 44'inserted in a suitable trans.- verse hole near the top of arm 32..

The lower end of hammer 31 is bifurcated as shown at 45 in Figs. 1 and'8. It-shouldbe. men.- tionedhere that hammer 31 is substantiallyshorter than the rectangular recess 36ito permit considerable longitudinal. movement of'su'ch hammer within recess 36. in order that" hammer 31' can obtain sufficient. momentum to strike firing; pin 24a smart blow.

A horizontal. longitudinally-extendinghole 46 is provided in the horizontal arm 31 of breech block carrier I4 to house a substantially. cylindrical sear 41. A tang 48 is provided on the rear end of sear 41 disposed at right angles to theaxis of the cylindrical body'of' such sear. Tang 4%! projects outwardly'somewhat beyond the side-of carrier I4 through a suitable horizontally disposed slot in such carrier. Sear 41" is arranged to bebiased forwardly by aspring 49 which is retained within a rearwardly opening bore 50 of sear 41.

A plug 5I placed in the end ofbore-50secures spring 49 and sear 41 in hole 46, such plug being in turn secured to carrier- I'4-by avertically disposed pin 52. A notch-53"- isprovided' on the forward end ofsear 41 so that the end-of hammer 31: can be engaged by such end of the sear and retained thereon untilreleased.

The'hammer 3.1 is'cocked by a.cocking--.membierz 54 comprising a substantially triangular member and is inserted in a slot 55 provided on the underside of carrier ML The cocking member 54 is pivotallymounted within slot- 55-'on-a transverse pin 51, such transverse pin however is of rectangular configuration where such pin passes through cocking member 54. A rectangular hole is of course provided in cocking memberlj54 to accommodate such rectangular portion of pin 51. One of the apexes 56 of cocking member 54 passes between the bifurcated end 45 of hammer 31 to force such hammer upwardly when the lower apex 58 of cocking member 54 strikes the sloped surface'59 on an upstanding lug 69 provided on bottom -plate I8 as carrier I4 moves rearwardly.

There is pivotally secured to the left end of pin 5 1,.assho-wn in Fig. 8, a firing pin retracting lever BI. Lever BI is secured to pin 51 in such fashion so as to permit limited pivotal movement of such lever about pin 51. An integral lug 62 is provided on the end of pin 51 which rests within a substantially V-shaped recess63provi'ded on the endof-l'ever 6I. A leaf spring 64 is secured: within a 'suita'ble recess in the underside of'a cross member 65 of carrier slide 35'. Leafspri'ng-M eX- tends forwardly and is provided'with a rounded end 66 as shown in Fig. 8. Such rounded-end contacts a projection 61 formed-by notchingthe rear corner of cooking member 54. Spring; 641sprovided to bias cocking member 54 upwardly and hence lever BI downwardly into the'path of 'a sloped end 68 of a reciprocable operatingslide 591 The forward end of lever 5| is provided witli a transversely outwardly projecting lug 10 teengage the rear end of operating slide 69;-

Operating slide 69 is provided to manuallycharge or load the firearm. Such slidelikewise provides means for retracting the firing-pin s-will be-presently described. This is quite necessary in the event a misfire should occur. Aswill be brought out later, ifthe action were retracted without retraction of the firing pin, the breech block I3 would slide down the breech blockca-r rier I4 and thus break the tip of the firingpin;

When operating slide 63 is retracted; theslope'd end 68 thereof strikes the lower corner of'fllug 11! of firing pin retracting lever 6|. Uponstrik'ing the end of suchlug, cocking-member54 is forced upwardly a slight amount which likewise forces hammer 31 upwardly. This upward movementof the hammer lifts lug 38-from the head 25 of firing pin 24. Firing pin 24 is then retracted lris" the bias of spring 21 until the slope corner'26- provided on the underside of'head'25 strikes plate 28. The forward end of' firing-pin. 24-wl11 then be sufiiciently retracted fromthe face of breech block I3 so that'there will be no-interference with the cartridge in the T-slot 22 of-such-block-. As the sloped surface-68 on the end cfoperating silde 69 strikes lug'lfl, lever fitis-raisediupwardly along such sloped surface until theextreme' rear end of lug 'lIlstrikes a shoulder 1I provided on-operating slide I39. Upon striking'shoulder T4, the-lever BI is prevented from rotating further a'n'dl hence carrier slide 35, carrier I4 and breech block I 3 will be moved rearwardly by operating slide 69:.

As-the recoilstroke is completed; cockinglmem ber 54 rides up-cam surface 59 oflug-50 and hammer 31 is raised: upwardly suffici'ently: to permit sear 41 under the bias of spring 49 to slide.under.= the bottomsend of'hammer 31' thuslretaining such hammer in the cocked position;

To release-sear 41, a sear release mechanism is utilized: comprising.- awedge-shapedrsear re lease-member12..(Figs.. 3 andz 6); which 1128:13 5

T-shaped base 13, and a trigger I4, is mounted on a bracket on the right side of the firearm as shown in Fig. 3., Bracket 15 is suitably secured to right side plate I! slightly ahead of sear tang 48 as shown in Fig; 3. A grip I6 is vertically mounted in bracket 15 as by a bolt 11. Trigger M comprises a substantially L-shaped member as best shown in Fig. 4 and is pivotally mounted on bracket 75 by a vertical pin 18. The forwardly projecting leg of trigger I4 is provided with an elongated hole 19 which is engaged by a vertical pin 80 in a sear release housing 8| as shown in Figs. 3 and 9. Pin 88 also passes through wedge shaped sear release member 12 thereby pivotally securing such member to housing 8i.

Housing BI is a substantially rectangular member and is mounted in a T-shaped slot 82 provided on top of bracket 75. The forward end of housing BI is bifurcated as shown at 83 to receive a sear release plunger 84. Sear release plunger 84 is a T-shaped member provided with a cylindrical stem portion 85 (Fig. 9). A spring 88 surrounds stem portion 85 to bias plunger 84 against T-shaped base 73 of sear release member 12. A spring-biased plunger 81 (Fig. 3) is inserted within a suitable hole in bracket 15 and engages the front surface of trigger in such fashion that trigger i l will be biased in a clockwise direction about pin 18.

The trigger mechanism illustrated in the appended drawings is utilized for semi-automatic fire. When the action is in the breeched or closed position shown in Fig. 1, sear 41 is released by pressing against trigger 14. Sear release member 72 which is pivotally secured to housing 8! is forced transversely across a tapered transverse slot 88 on the top edge of side plate H. The wedge-shaped nose of sear release member I2 then wedges between sear tang 48 and breech block carrier i4 and actuates sear 41 rearwardly thereby effecting release of firing pin 24. The rearward movement of carrierv M then rotates release member 12 rearwardly against the rear surface of tapered slot 88 whereupon such carrier and in fact the whole breech mechanism slides past such release member.

When barrel extension 12 has recoiled past the sear release member 12, plunger 84 biases such member forwardly into the path of counterrecoil movement of barrel extension I2. It should be mentioned here that the T-shaped head of plunger 84 contacts some portion of base 13 of release member 12 at all times. Thus regardless of what position the release member 12 may assume, such plunger will force member 12 to the position shown in Fig. 3 when the trigger is released as will be presently described. As the barrel extension I2 moves forwardly on the counter-recoil stroke, such extension strikes sear release member 12 rotating such release member forwardly until it strikes the forward sloped surface of tapered slot 88. whereupon thebreech mechanism will slide freely past sear release member 12. As the sear release member 12 has been thrust to one side, as just described, the weapon can not be fired automatically, the sear release member having been disconnected from sear l'i.

To again fire the weapon trigger 14 is released whereupon housing 8| is forced away from the gun through the connection of such housing to trigger 14 by the bias of plunger 84. Sear release member 12 is then returned to the position shown in Fig. 3 ready to effect release of scar 41 when trigger I4 is again actuated. It should be 6 understood thatsuch mechanism can be readily modified to permit automatic fire if desired.

A safety 88 comprising a knob portion 90 and a cylindrical stem portion 9| is mounted underneath housing 8| as shown in Fig. '7, so that the stem portion thereof can engage housing 8| in such fashion as to block the forward movement of such housing. A flattened portion 92 is provided in the center of stem portion 9!. In the position shown in Fig. 7, safety 89 is in the inoperative position. When such safety is rotated in a clockwise direction as shown in Fig. 9, the fiattened portion 92 is rotated into a transverse notch 93 provided on the bottom of housing 8! thereby effectively blocking any movement of such housing. Safety 89 is retained on bracket 15 by a spring clip 94 which surrounds the projecting end of stem portion 8i. Such spring clip likewise allows slight lateral movement of safety 89 which therefore permits use of a suitable detent (not shown) to yieldingly secure such safety in either the safe or fire position.

For a more detailed and complete description of the firearm embodying this invention, reference may be had to my copending application Serial No. 675,124 filed June 7, 1946, for Firearm and now matured into Patent No. 2,555,379.

It should thus be apparent from the above description of the preferred embodiment of this invention that there is here provided a unique firing mechanism for a firearm having a breech block slidably mounted on the breech block carrier for movement in a vertical as well as a horizontal plane. Such mechanism is also of positive operation and is of sturdy construction to insure long life.

I claim:

1. In a firearm having a receiver, a barrel extension slidably mounted in said receiver for reciprocating movement, a barrelsecured to said barrel extension, a breech block carrier slidably monuted in said receiver for reciprocating movement parallel to said barrel and barrel extension movement, a breech block guide surface on said carrier angularly disposed relative to the path of movement of said carrier and located rearwardly of said barrel extension, 2. breech block slidably mounted relative to said guide surface for reciprocal movement between two spaced positions on said guide surface, said guide surface having a longitudinal recess, a hammer slidably mounted in said recess, resilient means biasing said hammer downwardly, a sear horizontally mounted in said carrier constructed and arranged to engage the lowermost end of said hammer, means for cocking said hammer, and resilient means biasing said sear forwardly to engage said hammer when in the cooked position whereby said hammer is so held until release of said sear.

2. In a firearm having a receiver, a barrel extension slidably mounted in said receiver for reciprocating movement, a barrel secured to said barrel extension, a breech block carrier slidably mounted in said receiver for reciprocating movement parallel to said barrel movement, a breech block guide surface on said carrier angularly disposed relative to the path of movement of said carrier and located rearwardly of said barrel extension, a breech block slidably mounted relative to said guide surface for reciprocal movement between two spaced positions on said guide surface, a firing pin horizontally mounted in said breech block having a head portion provided with a sloped surface, said angularly disposed member, said triangular cocking memberbeingi pivotally mounted underneath said carrier, and

so arranged whereby one of the apexes; thereof contacts the bottom of said hammer, andIa'dow-n- Wardly projecting apex arranged to strike'an upright cam on the recoil movement of saidbreech block whereby said cocking member is.- rotated upwardly to cock said hammer.

4; In a firearm having a receiver, abarrelextension slidably mounted in said receiver for reciprocating movement, a barrel secured: to. said.

barrel extension, a breech block carrierslidably mounted in said receiver for reciprocating-movement parallel to said barrel and barrel-extension movement, a breech block guide surface on said carrier angularly disposed relative to the-path of movement of said carrier andlocated rearwardly of said barrel extension, a breech block slidably mounted relative to said guidesurface for reciprocal movement between two spaced positions on said guide surface, a firingpin in said breech block, resilient means surrounding said firing pin, a hammer mounted'in. said carrier constructed and arranged to strike saidfiring pin, a cocking member adapted to cock said hammer, an operating slide slidably mountedon.

said receiver, a retracting lever securedto said cocking member, and arranged for limitedpiv.- otal movement, said lever having a projecting lug on the free end thereof, and said operating slide having a cam surface on one end whereby said. cam surface contacts said. projecting lug on said lever when said slide is manually retracted thereby rotating said lever and cocking member taraise said hammer a limitedamount to;v permit said resilient means to retract said firingipin to prevent breakage of said'firing' pin.

5.- The combination defined in claim 4 including' a sear engageable with said hammer and a sear'release means therefor comprising, a bracket fixedly secured to the side of the receiver, a housing: slidably mounted in said bracket for transverse reciprocable movement, a T-shaped sear: release member, a pivot pin vertically mounted-in the front end of said housing for pivotally retaining said sear release member thereto, a trigger pivotally secured to said bracket and having a forwardly projecting arm, said arm having an elongated slot arranged to receive said pivot pin therethrough whereby pivotal movement of. said trigger efiects slidable movement ofsaidhousing, a spring-biased T-shaped plunger in saidhousing arranged to abut said T-shaped sear release member in back-to-back relationship whereby pivotal movement of said member depresses said plunger, said sear release member having a wedge-shaped front end arranged to be moved inwardly of the receiver into the path of movement of the recoiling breech block carrier and against said sear when said trigger is depressed whereby said sear is cammed rearwardly, out of engagement with said hammer, means in the receiver for limiting the pivotal movement of said sear release member, and spring means for urging said trigger to its prefired. position upon release thereof.

CLARENCE E. SIMPSON.

REFERENCES CITED The following references are of record in the file; of this patent:

UNITED STATES PATENTS Number Name Date 1,557,414 Browning Oct. 3, 1925. 1,805,601 Ross V May 19, 1931 1,911,859 Frommer May 30, 1933 2,376,057 Hyde May 15, 1945 

